Percentage Calculator
Calculate a percentage of any number, find what percentage one value is of another, or measure a percentage increase or decrease. Results update instantly as you type.
What is X% of Y?
Find a specific percentage of any number.
Calculated amount
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Formula: (X ÷ 100) × Y
X is what % of Y?
Convert a part-to-whole ratio into a percentage.
Percentage ratio
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Formula: (X ÷ Y) × 100
Percentage Change
Measure the increase or decrease from an original value to a new value.
Percentage change
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Formula: ((new − original) ÷ |original|) × 100
How to use the percentage calculator
Choose the question that matches what you know, enter the two values, and read the result below the fields. You do not need to press a submit button because the answer updates whenever either number changes.
- Use What is X% of Y? when you know a percentage and want to find the corresponding amount.
- Use X is what % of Y? when you know the part and the whole and want to convert that ratio into a percentage.
- Use Percentage Change when you have an original value and a new value and want to measure an increase or decrease.
Percentage formulas with examples
A percentage means “per hundred.” These three formulas cover the most common percentage questions in shopping, school, business, finance, and everyday calculations.
Find a percentage of a number
Formula: (percentage ÷ 100) × value
Example: 15% of 200 is (15 ÷ 100) × 200 = 30.
Find one number as a percentage
Formula: (part ÷ whole) × 100
Example: 45 out of 180 is (45 ÷ 180) × 100 = 25%.
Find a percentage change
Formula: ((new − original) ÷ |original|) × 100
Example: A rise from 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25%.
Common ways to use percentages
Percentages make values with different sizes easier to compare. You can use the calculator to check a sale discount, work out a tip, convert test marks into a grade, measure a salary increase, compare monthly sales, calculate a commission, or understand a gain or loss. For price-specific calculations, use the related discount, VAT, and tax tools below.
Always choose the correct baseline. Percentage change uses the original value, while percentage difference uses the average of two values. That distinction matters when comparing independent measurements rather than tracking a change over time.
Related percentage calculators
Use a focused calculator when your question needs a different baseline or a price-specific formula.
Percentage Increase Calculator
Measure how much a value has grown from its starting point.
Percentage Decrease Calculator
Work out the percentage reduction from an original value.
Percentage Difference Calculator
Compare two values when neither one is the original baseline.
Reverse Percentage Calculator
Find an original amount from a final value and percentage.
Discount Calculator
Calculate the amount saved and the final sale price.
VAT Calculator
Add VAT to a net price or remove it from a gross total.
Frequently asked questions
How do I calculate a percentage?
Divide the part by the whole and multiply by 100. For example, 20 divided by 50 is 0.4, and 0.4 multiplied by 100 is 40%.
How do I find a percentage of a number?
Divide the percentage by 100 and multiply it by the number. For example, 15% of 200 is 0.15 multiplied by 200, which equals 30.
How do I calculate percentage change?
Subtract the original value from the new value, divide that change by the absolute original value, and multiply by 100. A positive answer is an increase and a negative answer is a decrease.
What is the difference between percentage change and percentage difference?
Percentage change compares a new value with an original baseline. Percentage difference compares two values using their average when neither value is the natural starting point.
Can a percentage be greater than 100%?
Yes. A percentage is greater than 100% when the part is larger than the whole. For example, 150 is 150% of 100.
Why can percentage change not start from zero?
The standard percentage-change formula divides by the original value. When the original value is zero, that division is undefined, so a conventional percentage change cannot be calculated.